Composition of matter



Patented July 21, 1931 Unrrs sra'rss PATENT FFl CE GREGORY J". COMSTOGK, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO FIRTH- STERLING STEEL COMPANY, OF MCKEESPORT, I'ENNSYLVANIA, A CORPORATION OF PENNSYLVANIA No Drawing.

lhe present invention relates broadly to an improved composition of matter and more particularly to a'composition comprising the combination of a cutting agent or cutting agents of abrasive characteristics with a bind ing agent.

I have found that certain materials, which are hereinafter referred to as cutting agents,

when held together byindefinite percentages of a suitable binder, provide a composition of matter having such characteristics as to render them suitable for a wide variety of of purposes. Within the class of cutting agents are included such materials as silicon carbide, tungsten carbide, and vitrified zirconium oxide, these materials being consid ered as cutting or abrasive agents due to their extreme hardness. The utility of the'invention, however, is not limited necessarily with respect to the particular cutting agent employed, although those referred to give desirable results in accordance with the methods hereinafter described.

While the present invention adapts itself to the use of a wide variety of binders, I prefer to utilize a metallic binder comprising an alloy steel. By alloy steel I mean an ironcarbon alloy containing minor amounts of elements such as silicon, sulphur, phosphorus, and manganese, together with an alloying element. Within the classification designated by this title, I include preferably .manganese steels, high carbon-high chrome steels, oil-hardening steels, so-called stainless steels and irons, chrome vanadium steels, andhigh carbon chrome nickel steels. Each one of these alloys possesses characteristics when utilized in accordance with the present invention which impart desirable properties to the resulting product. The particular selection of the alloy steel is dependent upon the special use to which the product isto be applied.

I have thereto.

found that manganese steels as a binding agent are particularlydesirable by COMPOSITION or MATTER Application filed April 9, 1928. SerialNo. 268,390.

A typical example of manganese steel Wl11Cl1 may be utilized in accordance with this invention is the following:

The high carbon-high chrome steels likewlse have certain characteristics which pecuharly adapt them to use with cutting agents of the character herein contemplated. Like the .manganese steels, they have a high re.-

sistance to abrasion. In addition to this,

they, and the product resulting from their use, may be hardened in air, oil or water, thereby giving to such a steel a broad adaptability.

The following tables give both typical analyses and the usual variations of high carbonhigh chrome steels as herein contemplated Typical Usual variaanalysis ons Type A Per cent Per cent 25 35 .030 030 11. 50 10. 00-14. 00 1.00 1.25 Molybdenum 1. 00 75- 1.25 Balanceiron.

Type B Per cent Per cent 30 30 030 Phosphorus 030 Chromium 12. 50 10-14. 00 Balance-iron Oil-hardening steels possess the property of displaying a minimum dimensional change. as a result of heat: treatment. This renders them particularly applicable as a binder of the abrasive particles, in that the minimizing of the disposition to contract or expand greatly reduces the tendency to weaken the product by loosening the hold of the blIldlIW material upon the abrasive grains, through movement or permanent distortion. There are two general typesof oil-hardening steels which may be used in this way, examples of Typical Usual varia- WhlCll are shown in the following tables: analysis tions Typical Usual Type D analysis variations Per cent Per cent Type A Carbon 1O 07 to.

SlllOOD..- 30 Manganese. 40 Per cent Per cent Chrom1um 12. 00, 11.50 to 13. 50

0 70 m 1.00 p r---- 3 Ph0sphorus 030 V 1. co' 1. 40 t 1. so Nickel -00t01-00 iillllphlllln; .830 l v osp orus. Balance-iron. Chrome nadium steels are characteristically hard and tough and possess a re- TYPBB Inarkable high wear-resisting quality, and. are strongly coherent, making them partic- Carbon fgg fQ iZ ularly applicable as a metal binding agent Siliconfor the abraslve of this product. When Manganese. 1.50 1.40 to 1.80

prim" .030 properly heat treated, they display a high. ggggi ggg 128 L00 tensile strength coupled with good elastic Tlmgstenproperties. A steel of the type which I use The so-called stainless steels and irons possess the well recognized property of resist-.

and the combination of these properties makes them a desirable metal binding agent for use in this connection.

\ Tungsten carbide is not susceptible to corrosion, and therefore, when suitably united With a non-corrosive binding material, the

resulting product is also resistant to corrosion. The use of stainless steels and alloys is therefore extremely desirable. Examples of the typeswhich may beused in this connection are listed in the following tables:

Typical Usual variaanalysis ons Type A Per cent Per cent Carbon 35 25 to 45 8ilicon .20 M anganese" 30 romium 13. 50 11. 00 to 14. 00 Sulphur"- 030 Phosphorus 030 Balance-iron.

YP B 7 Per cent Per cent C a rbon 65 60 to .85 S1l1con 25 Manganese 36 Chromium 16. 50 16. 00 to 18. 00 Sulphur 030 Phosphorus 030 Balance-iron.

Type'C Per cent 6. 00 to 10.00 Balance-iron.

in this product is exemplified in the following table:

I have also found that a material, the character of which is in the zone between that of cast iron and a true steel possesses desirable attributes when used as a binding agent. When united with the abrasive according to this invention, this material is exceptionally hard and resistant to the action of abrasion under heat and is at the same time susceptible to considerable deformation in the hot condition. Thus it combines several desirable properties which make it specially suitable for use'as a binding agent.

A typical example of such a binding agent is shown in the following table:

In carryin out the present invention, I

V preferably ta e the desired cutting agent or mixture of cutting agents and ulverize the same to very finely divided con ition, preferably to a fineness which will pass through a two hundred mesh screen. The same procedure is followed with the binding agent.

The cutting agent or agents and the bind- Q ing agent having been reduced to the desired fineness, they are mixed together in varying proportions, depending upon the characteristics which are deslred 111 the final composition. lVhere brittleness of the product is no limiting factor, small percentages of binder may be used, but where strength and resistance to shock are required, larger percentages of binder must be present. It is notable that where the binder is increased, the cutting or abrading value of the abrasive and likewise the cutting or abrading value of the product is necessarily decreased, due to the relatively greater dispersion of the cutting particles. For example, in cases of the character first referred to, I may utilize as high as ninety-five percent of the cutting agent or cutting agents with desirable results, while in the latter case, the binding agent may be decreased up to ninety-five percent or even higher.

In some cases, I have found that beneficial results are obtained by the mere addition of a trace ofjthe cutting agent to a standard alloy steel of the character herein recited, and especially manganese alloys.

In some cases, it is desired to provide a composition of matter of such nature that it lends itself to shaping and deforming by hot working. In such cases, I utilize not less than thirty, and preferably not less than-fifty, percent of the binding agent, although variations in this amount may be made one way or the other, while retaining some degree of workability.

Example I A specific example of a composition suitable for use in the production of tools, such as drawing dies, extrusion dies, high speed cutting tools, such as bits, shapers. drills, cutters, saws, and the like, is as follows i Tungsten carbide, 87.00%, 13.00% of a manganese steel as herein referred to.

Example H Example I I I Where it is importantthat the resulting product have workable characteristics, Ihave found thata composition in accordance with the following gives desirable results:

Tungsten c a r b i d e 30.00%,- Manganese steel, as herein referred to, 7 0.00%.

Having determined upon the proper composition depending upon the character which the resulting product is to have for its specific application, I may proceed in accordance with any of four different methods. The

, ingredients.

plication of heat followed by the application of pressure, without any preliminary press- In accordance with the first method, which will hereinafter be referred to as the cold compacting method, I preferably form a paste by usinggum tragacanth in the amount of one ounce of the gum tragacanth to a pint of water and add this paste to the mixture of cutting agent or cutting agents and binding agent, inthe ratio of about one half of one percent by weight. This mixture is then subjected to pressure while cold, the pressure preferably being of the order of one hundred fifty tons to the square inch. This produces a closely compacted mixture which is then subjected'to a temperature sufficiently high to melt the binding agent and cause it to actually flow around the cutting agent or cutting agents, so that upon cooling, such agent or agents will be substantially uniformly dispersed or distributed throughout the product with each particle firmly bonded in the binding material, which in this case forms a metal matrix.

In the second method, the preliminary steps of forming a paste-like mixture and pressing the same are followed. Thereafter this mixture is subjected to heat to fuse the binding agent, and either simultaneously with the application of the heat, or subsequently thereto while the mixture 1s st1ll hot, is subjected to pressure.

In thethird method, the preliminary compacting is dispensed with, the mixture being pressure.

The second, third, and fourth methods have the advantage of providing pressure at such atime as to tend to close up any pores which may have formed under the'heat treatment by reason of the volatilization of any of the Also, these three last mentioned-processes require amaterially lower pressure, pressures as low as from seventy; five to one hundred fifty pounds per squareinch producing satisfactory results with some mixtures.

In heating, in each of the methods above referred to, I prefer to employ temperatures in the neighborhood of 2800 F., although it will be obvious that this temperature depends on vthe particular metallic binder employed and may vary within fairly wide limits. During the heating, suitable precautions must be taken to prevent oxidation of the product. This may be accomplished, for example, by heating in a reducing atmosphere of hydrogen.

In all cases where 'a paste has been formed by the use of gum tragacanth, the application of heat volatilizes the same from the mixture.

The hardness of the composition in accordance with my invention is such that once it has been produced, it does not lend itself to grinding or cutting by known methods. It is therefore desirable, in case the proportions are not such as to produce a workable product, i. e., a product lending itself to shaping or deformation when heated to a suitable temperature, to subject the mixture to pressure in a mold of the desired configuration of the finished article. pleted article, such as a tool, can be formed directly from the mixture.

While I have herein referred to certain specific types of alloy steels for the purpose of giving a clear understanding of my inven tion, it will be understood that the particular analyses set forth are given by way of illustration only and not by way of limitation.

Throughout the foregoing description Where I have referred to tungsten carbide, I preferably utilize a carbide having approximately six percent of carbon combined with the tungsten. I have found that the other carbides of tungsten produce compositions of materially different characteristics.

While in the specific examples herein given I have referred to the use'of tungsten carbide, this being the present referable cutting agent, either alone or 1n conjunction with other cutting agents of the character herein referred to, it will beunderstood that the other cutting agents may be utilized to replace or partly replace the tungsten carbide,

the results obtained varying with the characteristics of the particular cutting agent utilized.

It will be understood by those skilled in the art that the present invention, according to the best of our present knowledge, results purely in a mechanical mixture or aggregate, the different materials utilized not combining chemically to any material degree,

under the temperature and pressure conditions to which they are subjected.

It is to be understood that I have described the present preferred embodiment of my invention, but that it is not limited except as In this manner, a com-.

aggregate, the alloy steel containing about 320% manganese and about .65-125 carbon. In testimony whereof I have hereunto set my hand.

GREGORY J. COMSTOCK.

CERTIFICATE OF CORRECTION.

Patent No. 1,815,613. Grented July 21, 1-931, r

GREGORY J. COMSTOCK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 9, ion the 'word "indefinite' read definite; and that the said Letters Patent shouidiber wirh this correction therein that the same may conform to ihe record oi the case in the Patent (mice.

Signed ehd'seaied this ist'daymf September, A. D. 1931.

I M. (Seai) Acting Gemmissioner cfi'iarems. 

